Refrigerating system and thermostatic expansion valve thereof

ABSTRACT

A thermostatic expansion valve and a refrigerating system comprising the thermostatic expansion valve. The thermostatic expansion valve comprises a valve body arranged with an air box on the top, and the inner chamber of the air box is divided into an upper chamber and a lower chamber by a diaphragm. Within the inner chamber of the valve body there are provided a valve plug component and a valve port matched with the valve plug component. The inner chamber of the valve body is divided into a first interface chamber and a second interface chamber by a sealing line or sealing face between the valve port and the valve plug component. At the lower end part of the valve body there is provided a balance chamber to balance the valve plug component. The upper end part of the valve plug component is arranged within the lower chamber and the lower end part thereof is arranged within the balance chamber ( 14 ) of the valve body. The balance chamber is in communication with the lower chamber, and the balance chamber is in sealed isolation from both the first interface chamber and the second interface chamber. The structure of the thermostatic expansion valve is capable of reducing the systematic pressure difference to which the valve plug component is subjected, such that the regulating precision of the valve plug component is improved.

The present application is the US national phase of International Application No. PCT/CN2012/070276, filed on Jan. 12, 2012, which claims the priority from Chinese Patent Application No. 201110007936.3 titled “REFRIGERATING SYSTEM AND THERMAL EXPANSION VALVE THEREOF” and filed with the State Intellectual Property Office on Jan. 14, 2011, the entire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present application relates to the technical field of refrigerant fluid control components, and particularly to a thermal expansion valve. Moreover, the present application further relates to a refrigerating system including the thermal expansion valve.

BACKGROUND OF THE INVENTION

A thermal expansion valve is one of the important components composing a refrigerating system, and is one of the four essential components with the other three including an evaporator, a compressor, and a condenser in a refrigerating system. The thermal expansion valve mainly functions to control the size of opening of the valve by sensing the degree of superheating at the outlet end of the evaporator or the intake end of the compressor in the refrigerating system so as to regulate the flow of the refrigerant in the system, throttle and reduce the pressure.

Referring to FIG. 1, it is a schematic structural view of a typical thermal expansion valve in the prior art.

The thermal expansion valve includes a valve body V. The upper end of the valve body 1′ is connected with an air box including an air box base 2′4 and an air box cover 2′5. The inner chamber of the air box is partitioned into an upper chamber 2′2 and a lower chamber 2′3 by a diaphragm 2′1. As shown in FIG. 1, the upper chamber 2′2 is filled with refrigerant and connected to a temperature sensing bulb 4′2 via a capillary 4′1. The temperature sensing bulb 4′2 is configured to sense the degree of superheating of refrigerant at the outlet end of the evaporator and the inlet end of the compressor, and generate a temperature pressure P_(b) in the upper chamber. Meanwhile, the lower chamber 2′3 communicates with the outlet end of the evaporator via a balance tube (not shown), so as to generate an evaporating pressure P_(o) in the lower chamber 2′3.

Furthermore, as shown in FIG. 1, a valve port 1′1 is formed in the inner chamber of the valve body 1′ and fitted with a valve core 3′1. The upper end of the valve core 3′1 is connected with a transmission rod 3′2 which is connected to a transmission piece 3′3 located in the lower chamber. It is to be noted that, in the present prior art, the valve core 3′1, the transmission rod 3′2 and a guide ball 3′4 as described below are collectively referred to as a valve core component, which is therefore of a structure having separated parts in the present prior art. A guide ring 7′ is provided outside of the valve core 3′1. The chamber below the guide ring 7′ is a balance chamber 1′4 in which a spring 6′ supporting the valve core 3′1 is provided. The spring 6′ imparts an upward elastic force P_(t) to the valve core 3′1.

Taking the valve core 3′1 and the transmission rod 3′2 as objects for force analysis, the valve core 3′1 and the transmission rod 3′2 are subjected to both an upward elastic force P_(t) and a downward pushing force applied by the transmission piece 3′3. The diaphragm 2′1 pushes the transmission piece 3′3 so as to generate this pushing force, so the pushing force is just the force driving the diaphragm 2′1 to move downwards, i.e., P_(b)−P_(o). When the valve core 3′1 is in a balanced state, P_(b)−P_(o)=P_(t), i.e., P_(b)=P_(o)+P_(t). When the temperature at the outlet end of the evaporator is too high, the P_(b) increases, so that the valve core 3′1 is pushed to move downwards, thereby increasing the flow of the refrigerant. When the temperature at the outlet end of the evaporator is too low, the P_(b) decreases, so that the valve core 3′1 is pushed to move upwards, thereby decreasing the flow of the refrigerant.

However, as shown in FIG. 1, in the process of practical operation, in addition to the above temperature pressure P_(b), the evaporating pressure P_(o) and the elastic force P_(t) of a spring, the valve core 3′1 may be further subjected to a pressure for opening the valve core 3′1 generated by refrigerant in the first interface chamber 1′2 and a pressure for closing the valve core 3′1 generated in the second interface chamber 1′3, and the difference value between the two pressures generates a systematic pressure difference. For a valve with small capacity, or a low pressure refrigerating system, the effect of the systematic pressure difference on the valve core 3′1 may be substantially ignored. However, for a valve with large capacity or a high pressure refrigerating system, the effect of the systematic pressure difference on the valve core 3′1 is significant, with the result that the accuracy of the regulation of the valve core 3′1 is heavily influenced.

In view of this, as shown in FIG. 1, the valve core 3′1 is provided with a through hole 3′11 for communicating the first interface chamber 1′2 with the balance chamber 1′4. The lower end of the through hole 3′11 is fitted with a guide ball 3′4, and there is a clearance between the guide ball 3′4 and the through hole 3′11, so that pressures in the two chambers are equal to each other. Also, the force area of the second pressure-bearing surface S′2 in the first interface chamber 1′2 is equal to the force area of the first pressure-bearing surface S′1 in the balance chamber 1′4. Since the first pressure-bearing surface S′ 1 and the second pressure-bearing surface S′2 are subjected to opposite forces, the pressures on the valve core 3′1 generated by the refrigerant in the first interface chamber 1′2 counteract each other. As shown in FIG. 2, a third pressure-bearing surface S′3 and a fourth pressure-bearing surface S′4 subjected to opposite forces are provided in the second interface chamber 1′3. Since the force areas of the two pressure-bearing surfaces are equal to each other, the pressures on the valve core 3′1 generated by the refrigerant in the second interface chamber 1′3 counteract each other. Thus, no matter whether the refrigerant flows from the first interface chamber 1′2 to the second interface chamber 1′3, or from the second interface chamber 1′3 to the first interface chamber 1′2, the systematic pressure difference is substantially zero, and therefore the balanced flowing in double directions may be achieved through the thermal expansion valve.

Though the thermal expansion valve shown in FIG. 1 may achieve the balanced flowing in double directions, this kind of balance is only a rough balance, and the systematic pressure difference is not absolutely zero, that is, an absolute balance has not achieved yet. Specifically, as shown in FIG. 1, since the transmission piece 3′3 and the transmission rod 3′2 are connected with a clearance therebetween, the pressure of the refrigerant in the lower chamber 2′3 acts on the upper end surface of the transmission rod 3′2, and further results in a downward force on the valve core 3′1. Due to the resulting force, the systematic pressure difference cannot be absolute zero, and therefore, the accuracy of the regulation of the valve core 3′1 may yet be influenced.

It is to be noted that, when the transmission piece 3′3 and the transmission rod 3′2 are connected in a completely sealed manner without any clearance therebetween, taking the transmission piece 3′3, the transmission rod 3′2 and the valve core 3′1 as a whole as an object for force analysis, the top surface of the transmission piece 3′3 may be still subjected to a downward force generated from the pressure of the refrigerant in the lower chamber 2′3, and the area subjected to this applied force is just the sealing area between the transmission rod 3′2 and the transmission piece 3′3, i.e., the area of the upper end surface of the transmission rod 3′2. Therefore, the valve core 3′1 may be still subjected to an applied downward force. Due to the resulting force, the systematic pressure difference cannot be absolutely zero, and therefore, the accuracy of the regulation of the valve core 3′1 may yet be influenced.

Furthermore, the following deficiencies still exist in the thermal expansion valve shown in FIG. 1:

First, the transmission rod 3′2, the valve core 3′1 and the guide ball 3′4 are provided separately. Thus, the number of the parts is huge, resulting in a relatively big accumulated dimension tolerance in the axial direction, a reduced accuracy of the regulation and a reduced performance of the thermal expansion valve, and a cumbersome assembly.

Second, the balance chamber 1′4 communicates with the first interface chamber 1′2, and when the first interface chamber 1′2 is a high pressure end, pressure in the balance chamber 1′4 is high, which imposes high requirement on the sealing and increases the risk of leakage.

Third, providing the through hole 3′11 in the relatively small valve core 3′1 causes a difficult processing.

SUMMARY OF THE INVENTION

One technical problem to be solved by the present application is to provide a thermal expansion valve, which is structured to reduce the systematic pressure difference applied to the valve core component, so that the accuracy of the regulation of the valve core component may be improved. Furthermore, another technical problem to be solved by the present application is to provide a refrigerating system including the thermal expansion valve.

To solve the above technical problem, the present application provides a thermal expansion valve, including a valve body. An air box is provided at the upper end of the valve body. The inner chamber of the air box is partitioned into an upper chamber and a lower camber by a diaphragm. A valve core component and a valve port fitted with the valve core component are provided in the inner chamber of the valve body. The lower end portion of the valve body is further provided with a balance chamber configured to balance the valve core component. The upper end portion of the valve core component is arranged in the lower chamber, and the lower end portion of the valve core component is arranged in the balance chamber of the valve body. The balance chamber communicates with the lower chamber, and is sealed to be isolated from the inner chamber of the valve body.

Preferably, a projected area of an upper pressure-bearing surface, subjected to pressure in the lower chamber, of the upper end portion of the valve core component on a plane perpendicular to an axis of the valve core component is substantially equal to a projected area of a lower pressure-bearing surface, subjected to pressure in the balance chamber, of the lower end portion of the valve core component on a plane perpendicular to the axis of the valve core component.

Preferably, when the valve core component and the valve port are closed, a sealing line or a sealing surface between the valve port and the valve core component partitions the inner chamber of the valve body into a first interface chamber and a second interface chamber. A first pressure-bearing surface and a second pressure-bearing surface subjected to opposite forces are provided on the side wall of the valve core component in the first interface chamber.

Preferably, the projected area of the first pressure-bearing surface on the plane perpendicular to the axis of the valve core component is substantially equal to the projected area of the second pressure-bearing surface on the plane perpendicular to the axis of the valve core component.

Preferably, a third pressure-bearing surface and a fourth pressure-bearing surface subjected to opposite forces are provided on the side wall of the valve core component in the second interface chamber.

Preferably, the projected area of the third pressure-bearing surface on the plane perpendicular to the axis of the valve core component is substantially equal to the projected area of the fourth pressure-bearing surface on the plane perpendicular to the axis of the valve core component.

Preferably, the valve core component is provided with an inclined sealing surface for sealing the valve port. When the valve core component and the valve port are closed, a sealing line between the valve core component and the valve port partitions the inclined sealing surface into the second pressure-bearing surface in the first interface chamber and the third pressure-bearing surface in the second interface chamber.

Preferably, the balance chamber communicates with the outlet end of the evaporator.

Preferably, the valve body is provided therein with a communicating hole communicating with the lower chamber. The communicating hole communicates with the balance chamber via first capillary arranged outside the valve body.

Preferably, the side wall of the valve body is provided with a first mounting hole communicating with the communicating hole, and a second mounting hole communicating with the balance chamber. One end of the first capillary is arranged in the first mounting hole, and the other end of the first capillary is arranged in the second mounting hole.

Preferably, the air box includes an air box base connected to the valve body. Each of the first mounting hole and the second mounting hole is arranged obliquely such as to have a downward inner end and an upward outer end, no matter whether the air box base is positioned upwards or downwards.

Preferably, the angle between the axis of the first mounting hole and the axis of the valve body is equal to the angle between the axis of the second mounting hole and the axis of the valve body.

Preferably, the air box includes an air box base connected to the valve body. No matter whether the air box base is positioned upwards or downwards, the side wall of the valve body is provided thereon with an inclined surface having an inward upper end and an outward lower end, so that the first capillary rests against the inclined surface.

Preferably, a capillary groove is provided in the side wall of the valve body, and the first capillary is arranged in the capillary groove.

Preferably, a connecting hole is integrally formed and communicates with the communicating hole and is located below the communicating hole. The connecting hole directly communicates with the balance chamber.

Preferably, the upper pressure-bearing surface of the valve core component is connected to a transmission piece with a clearance between the upper pressure-bearing surface and the transmission piece. The valve core component is provided with a valve core component through hole in an axial direction, and the lower chamber communicates with the balance chamber via the valve core component through hole.

Preferably, the upper end portion of the valve body is provided with an annular chamber, and an elastic component is provided in the annular chamber. The bottom end of the elastic component is supported on the bottom wall of the annular chamber or on a first spring seat, and the top end of the elastic component supports a transmission piece connected to the valve core component.

Preferably, the annular chamber further communicates with the balance chamber via the first capillary.

Preferably, a guide component is provided outside of the valve core component and is arranged in the inner chamber of the lower end portion of the valve body. The balance chamber is sealed to be isolated from the second interface chamber by means of the guide component and the sealing member arranged on the guide component. The opening in the lower portion of the balance chamber is threadingly connected with a valve bonnet configured to support the guide component.

Preferably, a clamping depression for being clamped by a clamping tool is provided on an external portion of the lower end portion of the valve core component in the balance chamber.

Furthermore, to solve the above technical problems, the present application further provides a refrigerating system, including an evaporator. The heat exchange device further includes any thermal expansion valve described above. The upper chamber is connected to the outlet end of the evaporator via a temperature sensing component, and the lower chamber communicates with the outlet end of the evaporator via a balance tube.

Based on the above prior art, the thermal expansion valve of the present application is improved in that the lower chamber of the air box communicates with the balance chamber which is sealed to be isolated from the inner chambers of the valve body. Since the lower chamber communicates with the balance chamber, the pressures in the lower chamber and in the balance chamber are equal to each other. Thus, when the projected area of the upper pressure-bearing surface of the valve core component on the plane perpendicular to the axis of the valve core component is equal to the projected area of the lower pressure-bearing surface of the valve core component on the plane perpendicular to the axis of the valve core component, the force applied to the valve core component by the refrigerant in the lower chamber and the force applied to the valve core component by the refrigerant in the balance chamber are equal but opposite to each other and thus counteract each other, so that the systematic pressure difference applied to the valve core component is reduced effectively. It is to be noted that, even when the projected area of the upper pressure-bearing surface of the valve core component on the plane perpendicular to the axis of the valve core component is not equal to the projected area of the lower pressure-bearing surface of the valve core component on the plane perpendicular to the axis of the valve core component, since the pressures in the two chambers are equal to each other, the structural design may reduce the systematic pressure difference applied to the valve core component as compared with the prior art.

In summary, the thermal expansion valve according to the present application is capable of reducing the systematic pressure difference applied to the valve core component, so that the accuracy of the regulation of the valve core component is improved.

Furthermore, the refrigerating system including the above thermal expansion valve according to the present application has the same technical effects as those of the above thermal expansion valve, which is therefore omitted for simplicity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural view of a typical thermal expansion valve in the prior art;

FIG. 2 is a schematic structural view of a thermal expansion valve in a first embodiment of the present application;

FIG. 3 is a side view of the thermal expansion valve in FIG. 2;

FIG. 4 is a schematic structural view of a thermal expansion valve in a second embodiment of the present application;

FIG. 5 is a side view of the thermal expansion valve in FIG. 4;

FIG. 6 is a schematic structural view of a thermal expansion valve in a third embodiment of the present application;

FIG. 7 is a schematic structural view of a thermal expansion valve in a fourth embodiment of the present application;

FIG. 8 is a side view of the thermal expansion valve in FIG. 7;

FIG. 9 is a schematic structural view of a thermal expansion valve in a fifth embodiment of the present application;

FIG. 10 is a side view of the thermal expansion valve in FIG. 9;

FIG. 11 is a schematic structural view showing the mounting of a first capillary of a thermal expansion valve in a sixth embodiment of the present application;

FIG. 12 is a schematic structural view showing the mounting of a first capillary of a thermal expansion valve in a seventh embodiment of the present application;

FIG. 13 is a schematic structural view of a thermal expansion valve in an eighth embodiment of the present application;

FIG. 14 is a side view of the thermal expansion valve in FIG. 13;

FIG. 15-1 is a schematic structural view of a valve core component of the thermal expansion valve in FIGS. 1 to 10;

FIG. 15-2 is a top view of the valve core component in FIG. 15-1;

FIG. 15-3 is a bottom view of the valve core component in FIG. 15-1;

FIG. 15-4 is a sectional view of the valve core component in FIG. 15-1 taken along line A-A;

FIG. 15-5 is a sectional view of the valve core component in FIG. 15-1 taken along line B-B; and

FIG. 15-6 is a sectional view of the valve core component in FIG. 15-1 taken along line C-C.

Specifically, the correspondence between reference numerals in FIG. 1 and names of the components is listed as follows:

1′ valve body; 1′1 valve port; 1′2 first interface chamber; 1′3 second interface chamber; 1′4 balance chamber; 2′1 diaphragm; 2′2 upper chamber; 2′3 lower chamber; 2′4 air box base; 2′5 air box cover; 3′1 valve core; 3′11 through hole; 3′2 transmission rod; 3′3 transmission piece; 3′4 guide ball; S′1 first pressure-bearing surface; S′2 second pressure-bearing surface; S′3 third pressure-bearing surface; S′4 fourth pressure-bearing surface; 4′1 capillary; 4′2 temperature sensing bulb; 6′ spring; 7′ guide ring.

Specifically, the correspondence between the reference numerals in FIGS. 2 to 12 and names of the components is listed as follows:

1 valve body; 11 valve port; 12 first interface chamber; 13 second interface chamber; 14 balance chamber; 15 communicating hole; 151 connecting hole; 16 outer balance connector; 17 first mounting hole; 18 second mounting hole; 19 inclined surface; 21 diaphragm; 22 upper chamber; 23 lower chamber; 24 air box base; 25 air box cover; 3 valve core component 31 sealing line; 32 transmission piece; 33 valve core component through hole; 34 clamping depression; 35 sealing member; 36 upper segment; 37 middle segment; 38 lower segment; S1 first pressure-bearing surface; S2 second pressure-bearing surface; S3 third pressure-bearing surface; S4 fourth pressure-bearing surface; S5 upper pressure-bearing surface; S6 lower pressure-bearing surface; 41 first capillary; 42 second capillary; 43 capillary groove; 5 annular chamber; 6 elastic component; 61 first spring seat; 62 second spring seat 63 third spring seat; 7 guide component; 71 sealing member; 72 snap spring; 81 valve bonnet; 82 regulating seat; 83 regulating rod.

DETAILED DESCRIPTION OF THE INVENTION

An aspect of the present application is to provide a thermal expansion valve, which has a structural design capable of reducing the systematic pressure difference across the valve core component, so as to improve the accuracy of the regulation of the valve core component. Furthermore, another aspect of the present application is to provide a refrigerating system including the thermal expansion valve.

For those skilled in the art to understand better the technical solutions of the present application, the present application will be further explained in detail in conjunction with the accompanying drawings and the specific embodiments.

It is to be noted that all of the term “above, under, left and right” as used herein take the location shown in the accompanying drawings for reference, and therefore cannot be construed as limiting the scope of protection of the present application.

Referring to FIGS. 2, 3 and 15-1 to 15-6, FIG. 2 is a schematic structural view of the thermal expansion valve in a first embodiment of the present application; FIG. 3 is a side view of the thermal expansion valve in FIG. 2; FIG. 15-1 is a schematic structural view of the valve core component of the thermal expansion valves in FIGS. 1 to 10; FIG. 15-2 is a top view of the valve core component in FIG. 15-1; FIG. 15-3 is a bottom view of the valve core component in FIG. 15-1; FIG. 15-4 is a sectional view of the valve core component in FIG. 15-1 taken along line A-A; FIG. 15-5 is a sectional view of the valve core component in FIG. 15-1 taken along line B-B; and FIG. 15-6 is a sectional view of the valve core component in FIG. 15-1 taken along line C-C.

In the fundamental technical solution of the present application, as shown in FIG. 2, the thermal expansion valve includes a valve body 1. An air box including an air box base 24 and an air box cover 25 is provided on the upper end of the valve body 1. The air box is provided therein with a diaphragm 21 configured to partition the inner chamber of the air box into an upper chamber 22 and a lower chamber 23. Specifically, as shown in FIG. 2, the upper chamber 22 is connected to a temperature sensing component (not shown) via a second capillary 42. The temperature sensing component is arranged at the outlet end of the evaporator or the inlet end of the compressor to sense the temperatures of the refrigerant at those locations and to generate a temperature pressure P_(b) in the upper chamber. As shown in FIG. 3, the lower chamber 23 communicates with the outer balance connector 16 via the communicating hole 15, and the outer balance connector 16 further communicates with the outlet end of the evaporator or the inlet end of the compressor via a balance tube, so as to generate an evaporating pressure P_(o) in the lower chamber.

Furthermore, as shown in FIG. 2, the inner chamber of the valve body 1 is provided therein with a valve port 11 fitted with a valve core component 3. When the valve core component 3 and the valve port 11 are closed, i.e., when the expansion valve is closed, the sealing line 31 (it is to be appreciated by the person skilled in the art that the sealing line 31 is just the area where the valve core component 3 contacts the valve port 11, also called the sealing surface) between the valve port 11 and the valve core component 3 partitions the inner chamber of the valve body 1 into a first interface chamber 12 and a second interface chamber 13 (it is to be noted that, in the present application, the meaning of the inner chamber of the valve body 1 only includes the first interface chamber 12 and the second interface chamber 13). The upper end of the valve core component 3 is arranged in the lower chamber 23 and the lower end of the valve core component 3 is arranged in the balance chamber 14 of the valve body 1. As show in FIG. 2, the balance chamber 14 is sealed to be isolated from the second interface chamber 13 via the guide component 7 and the sealing member 71 arranged on the guide component 7. The guide component is supported and located by a snap spring 72, and an elastic component 6 is provided in the balance chamber 14 (it is to be noted that, as shown in FIGS. 9 and 10, the elastic component 6 may also be arranged in the annular chamber 5 at upper end portion of the valve body 1) and configured to apply an upward elastic force P_(t) to the valve core component 3.

Taking the valve core component 3 as an object for force analysis, the valve core component 3 is subjected to both an upward elastic pressure P_(t), and a downward pushing force applied by the transmission piece 32. The diaphragm 21 pushes the transmission piece 32 to form the pushing force, and the pushing force therefore is just the force driving the diaphragm 21 to move downwards, i.e., P_(b)−P_(o). When the valve core component 3 is in a balanced state, P_(b)−P_(o)=P_(t), i.e., P_(b)=P_(o)+P_(t). When the temperature of the outlet end of the evaporator is too high, the P_(b) increases, so that the valve core component 3 is pushed to move downwards, thereby increasing the flow of the refrigerant. When the temperature of the outlet end of the evaporator is too low, the P_(b) decreases, so that the valve core component 3 is pushed to move upwards, thereby decreasing the flow of the refrigerant.

Based on the above prior art, the thermal expansion valve of the present application is improved in that the lower chamber 23 of the air box communicates with the balance chamber 14 which is sealed to be isolated from both the first interface chamber 12 and the second interface chamber 13. Since the lower chamber 23 communicates with the balance chamber 14, the pressures in the lower chamber 23 and in the balance chamber 14 are equal to each other. Thus, as shown in FIGS. 15-1, 15-2 and 15-3, when the projected area ΔS5 of the upper pressure-bearing surface S5 of the valve core component 3 on the plane perpendicular to the axis of the valve core component 3 is substantially equal to the projected area ΔS6 of the lower pressure-bearing surface S6 of the valve core component 3 on the plane perpendicular to the axis of the valve core component 3, the force applied to the valve core component 3 by the refrigerant in the lower chamber 23 and the force applied to the valve core component 3 by the refrigerant in the balance chamber 14 are equal but opposite to each other and thus counteract each other, so that the systematic pressure difference applied to the valve core component 3 is reduced effectively. Furthermore, even when the projected area of the upper pressure-bearing surface S5 of the valve core component 3 on the plane perpendicular to the axis of the valve core component 3 is not equal to the projected area of the lower pressure-bearing surface S6 of the valve core component 3 on the plane perpendicular to the axis of the valve core component 3, since the pressures in the two chambers are equal to each other, the structural design may reduce the systematic pressure difference applied to the valve core component 3 as compared with the prior art. It is to be noted that, the meaning of the expression “projected areas are substantially equal to each other” or the like includes ±5% deviation, in addition to a complete equivalence.

It is to be noted that, first, in the present fundamental technical solution, the present application focuses on whether the lower chamber 23 communicates with the balance chamber 14 or not, rather than by which structure the lower chamber 23 communicates with the balance chamber 14, and therefore, any structural design, so long as it enables the lower chamber 23 to communicate with the balance chamber 14, should fall into the scope of protection of the present application; second, in the fundamental technical solution, the structure of the valve core component 3 is not limited in the present application, for example, the valve core component 3 may be of a structure having separated parts (i.e., including the valve core 3′1 and the transmission rod 3′2) in the prior art as described above, or may be an integrated part in FIGS. 2 and 3 of the present application, or of course may be of any other structure; third, in the present fundamental technical solution, the thermal expansion valve is not limited in the present application to have the first pressure-bearing surface S1, the second pressure-bearing surface S2, the third pressure-bearing surface S3 and the fourth pressure-bearing surface S4 or not, and so long as the lower chamber 23 communicates with the balance chamber 14, regardless of whether having the above four pressure-bearing surfaces or not, the thermal expansion valves should fall into the scope of protection of the present application.

The above fundamental technical solution may further be improved. For example, referring to FIG. 2, a first pressure-bearing surface S1 and a second pressure-bearing surface S2 are provided on the side wall of the valve core component 3 in the first interface chamber 12, with the two pressure-bearing surfaces being subjected to opposite forces. Also, as shown in FIGS. 15-4 and 15-5, the projected area ΔS1 of the first pressure-bearing surface S1 on the plane perpendicular to the axis of the valve core component 3 is substantially equal to the projected area ΔS2 of the second pressure-bearing surface S2 on the plane perpendicular to the axis of the valve core component 3. Further, since the pressures applied to the first pressure-bearing surface S1 and the second pressure-bearing surface S2 are equal to each other, the systematic pressures applied to the valve core component 3 by the refrigerant in the first interface chamber 12 may cancel out each other. It is to be noted that, even when the projected area of the first pressure-bearing surface S1 on the plane perpendicular to the axis of the valve core component 3 is not equal to the projected area of the second pressure-bearing surface S2 on the plane perpendicular to the axis of the valve core component 3, the pressure applied to the valve core component 3 by refrigerant in the first interface chamber 12 may partially cancel out, and therefore the systematic pressure difference applied to the valve core component 3 may be reduced as well.

In the prior art as shown in FIG. 1, first, the first pressure-bearing surface S′1 is provided in the balance chamber 1′4, and the valve core 3′1 is provided with a through hole 3′11 for communicating the two chambers, accordingly causing the valve body component to adopt a structure having separated parts, i.e., including a valve core 3′1, a transmission rod 3′2 and a guide ball 3′4. Thus, more parts are used, resulting in bigger accumulated axial dimension tolerance. Second, the balance chamber 1′4 communicates with the first interface chamber 1′2, and when the first interface chamber 1′2 is a high pressure end, the pressure in the balance chamber 1′4 is high, which causes a high sealing requirement and also an increased risk of leakage. Third, providing the through hole 3′11 in the small valve core 3′1 causes a difficult processing.

However, in the present application, each of the first pressure-bearing surface S1 and the second pressure-bearing surface S2 is provided in the first interface chamber 12, so there is no necessary to provide a through hole in the valve core component 3, and further no necessary to provide a guide ball and a transmission rod. Thus, the valve core component 3 may adopt an integrated structure with only one part, so as to ensure the axial dimension tolerance and improve the accuracy of the regulation. Second, since there is no necessary to provide a through hole in the valve core component 3, so that the balance chamber 14 does not communicate with the first interface chamber 12, when the first interface chamber 12 is a high pressure end, the pressure in the balance chamber 14 is relatively low, which has low sealing requirement and thus reduces the risk of leakage. Third, the processing of providing a through hole in the valve core component 3 is omitted, so that the processing becomes easy and the processing cost is reduced.

The above fundamental technical solution may further be improved. For example, as shown in FIG. 2, a third pressure-bearing surface S3 and a fourth pressure-bearing surface S4 are provided on the side wall of the valve core component 3 in the second interface chamber 13, with the two pressure-bearing surfaces being subjected to opposite forces. Also, as shown in FIGS. 15-5 and 15-6, the projected area ΔS3 of the third pressure-bearing surface S3 on the plane perpendicular to the axis of the valve core component 3 is substantially equal to the projected area ΔS4 of the fourth pressure-bearing surface S4 on the plane perpendicular to the axis of the valve core component 3. Further, since the pressures applied to the third pressure-bearing surface S3 and the fourth pressure-bearing surface S4 are equal to each other, the systematic pressures applied to the valve core component 3 by the refrigerant in the second interface chamber 13 may cancel out each other. It is to be noted that, even when the projected area of the third pressure-bearing surface S3 on the plane perpendicular to the axis of the valve core component 3 is not equal to the projected area of the fourth pressure-bearing surface S4 on the plane perpendicular to the axis of the valve core component 3, the pressure applied to the valve core component 3 by refrigerant in the second interface chamber 13 may partially cancel out, thereby reducing the systematic pressure difference applied to the valve core component 3 as well.

Specifically, in the above fundamental technical solution, when the valve core component 3 is closed, if the refrigerant flows from the first interface chamber 12 to the second interface chamber 13, the pressures applied to the first pressure-bearing surface S1 and the second pressure-bearing surface S2 are equal but opposite to each other, and the third pressure-bearing surface S3 and the fourth pressure-bearing surface S4 are not subjected to the pressures from the refrigerant. Also, the upper pressure-bearing surface S5 and the lower pressure-bearing surface S6 of the valve core component 3 are not subjected to the pressures from the refrigerant as well. Further, since the force area of the first pressure-bearing surface S1 is equal to the force area of the second pressure-bearing surface S2, the pressures applied to the valve core component 3 by the refrigerant in the system are balanced, and thus the valve core component 3 is not affected by the fluctuation of the pressure of the refrigerant in the system. Similarly, when the valve core component 3 is closed, if the refrigerant flows from the second interface chamber 13 to the first interface chamber 12, with the analysis process substantially opposite to the above process, the pressures applied to the valve core component 3 by the refrigerant in the system are balanced, and thus the valve core component 3 is not affected by the fluctuation of the pressure of the refrigerant in the system.

After the valve core component 3 is opened, if the refrigerant flows from the first interface chamber 12 to the second interface chamber 13, pressures from high-pressure fluid are applied to the first pressure-bearing surface 51 and the second pressure-bearing surface S2 in opposite directions; pressures from low pressure fluid after being throttled are applied to the third pressure-bearing surface S3 and the fourth pressure-bearing surface S4 in opposite directions; and pressures from fluid at the outlet end of the evaporator are applied to the upper pressure-bearing surface S5 and the lower pressure-bearing surface S6 of the valve core component 3 in opposite directions. Since the force area of the first pressure-bearing surface S1 is equal to the force area of the second pressure-bearing surface S2, and the force area of the third pressure-bearing surface S3 is equal to the force area of the fourth pressure-bearing surface S4, and the force area of the upper pressure-bearing surface S5 of the valve core component 3 is equal to the force area of the lower pressure-bearing surface S6 of the valve core component 3, the pressures applied to the valve core component 3 by the refrigerant in the system are balanced, and thus the valve core component 3 is not affected by the fluctuation of the pressure of the refrigerant in the system. Similarly, when the valve core component 3 is opened, if the refrigerant flows from the second interface chamber 13 to the first interface chamber 12, with the analysis process substantially opposite to the above process, the pressures applied to the valve core component 3 by the refrigerant in the system are balanced, and thus the valve core component 3 is not affected by the fluctuation of the pressure of the refrigerant in the system.

In summary, the thermal expansion valve according to the present application may achieve a balanced flowing in double directions, and the balance in the present application is a perfect balance which is different from only a rough balance in the prior art.

In the above fundamental technical solution, a structure for communicating the lower chamber 23 with the balance chamber 14 may be specifically configured. Specifically, referring to FIGS. 3, 4, and 5, FIG. 4 is a schematic structural view of a thermal expansion valve in a second embodiment of the present application, and FIG. 5 is a side view of the thermal expansion valve in FIG. 4.

As shown in FIGS. 3 and 5, the valve body 1 is provided with a communicating hole 15 communicating with the lower chamber 23, and the communicating hole 15 is connected with an outer balance connector 16 which further communicates with the outlet end of the evaporator via a balance tube, so as to communicate the lower chamber 23 and the outlet end of the evaporator. Based on this, the communicating hole 15 further communicates with the balance chamber 14. This structural design utilizes the existing communicating hole 15, thus enabling the structure for communicating the lower chamber 23 with the balance chamber 14 to be simpler.

Specifically, as shown in FIG. 5, a connecting hole 151 is integrally formed and communicates with the communicating hole 15 and is located below the communicating hole 15, and directly communicates with the balance chamber 14. In this structural design, the communicating hole 15 and the connecting hole 151 are formed integrally in the same procedure. That is, the connecting hole 151 is formed to directly reach the balance chamber 14, so that the lower chamber 23 and the balance chamber 14 communicate with each other. Apparently, such a structural design further simplifies the structure for communicating the lower chamber 23 with the balance chamber 14, and the processing cost is reduced.

Furthermore, based on the communicating hole 15, another communicating structure may further be adopted. For example, as shown in FIG. 3, a connecting hole 151 is integrally formed and communicates with the communicating hole 15 and is located below the communicating hole 15, and communicates with the balance chamber 14 via a first capillary 41 arranged outside the valve body 1. In the technical solution shown in FIG. 5, though the communicating structure in which the connecting hole 151 is formed to directly reach the balance chamber 14 is very simple, processing is difficult due to the relatively big axial dimension and the relatively small diameter of the hole. However, in the technical solution shown in FIG. 3, the connecting hole 151, instead of being formed to reach the balance chamber 14, communicates with the balance chamber 14 via the first capillary 41. Therefore, the processing of the connecting hole 151 becomes easy.

Further improvement may be made based on the above communicating structure. Referring to FIGS. 11 and 12, FIG. 11 is a schematic structural view showing the mounting of a first capillary of the thermal expansion valve in a sixth embodiment of the present application, and FIG. 12 is a schematic structural view showing the mounting of a first capillary of the thermal expansion valve in a seventh embodiment of the present application.

Specifically, the side wall of the valve body 1 is provided with a first mounting hole 17 communicating with the connecting hole 151, and a second mounting hole 18 communicating with the balance chamber 14. One end of the first capillary 41 is arranged in the first mounting hole 17, with the other end thereof being arranged in the second mounting hole 18.

Further, as shown in FIG. 11, no matter whether the air box base 24 is positioned below the valve body 1, or the valve body 1 is positioned below the air box base 24, each of the first mounting hole 17 and the second mounting hole 18 is arranged to be inclined, having a downward inner end and an upward outer end. Such a structural design may facilitate hanging the first capillary 41 in the first mounting hole 17 and the second mounting hole 18, and may avoid the first capillary 41 from falling off, so as to facilitate the assembling between the first capillary 41 and the valve body 1. Specifically, as shown in FIG. 11, the angle between the axis of the first mounting hole 17 and the axis of the valve body 1 is indicated as α, and the angle between the axis of the second mounting hole 18 and the axis of the valve body 1 is indicated as β. The two angles may be equal to each other.

Furthermore, as shown in FIG. 12, no matter whether the air box base 24 is positioned below the valve body 1 or the valve body 1 is positioned below the air box base 24, the side wall of the valve body 1 is provided with an inclined surface 19 having an inward upper end and an outward lower end. As shown in FIG. 2, the inclined surface is at an angle of θ with respect to the axis of the valve body, and the first capillary 41 rests against the inclined surface 19. The inclined surface 19 may be structured to support the first capillary 41, so as to prevent the first capillary 41 from falling from the first mounting hole 17 and the second mounting hole 18.

Further, as shown in FIGS. 11 and 12, the side wall of the valve body 1 may be provided with a capillary groove 43, and the first capillary 41 may be arranged in the capillary groove 43. The capillary groove 43 may function to protect the first capillary 41 so as to prevent the first capillary 41 from being damaged.

Referring to FIG. 6, it is a schematic structural view of the thermal expansion valve in a third embodiment of the present application.

In this embodiment, the upper pressure-bearing surface S5 of the valve core component 3 is connected to the transmission piece 32 with a clearance therebetween. Based on this, the valve core component 3 is provided with a valve core component through hole 33 in an axial direction so that the lower chamber 23 communicates with the balance chamber 14 via the valve core component through hole 33. Apparently, such a structure may be used to communicate the lower chamber 23 and the balance chamber 14 as well.

Referring to FIGS. 9 and 10, FIG. 9 is a schematic structural view of a thermal expansion valve in a fifth embodiment of the present application; and FIG. 10 is a side view of the thermal expansion valve in FIG. 9.

Further improvements may be made as well based on any of the above technical solutions. For example, the elastic component 6 may be arranged at the upper end portion of the valve body 1. Specifically, as shown in FIGS. 9 and 10, the upper end portion of the valve body 1 is provided with an annular chamber 5 communicating with the lower chamber 23. An elastic component 6 is provided in the annular chamber 5, with the bottom end of the elastic component 6 being supported on the bottom wall of the annular chamber 5, and the top end thereof supporting a transmission piece 32 connected with the valve core component 3. As shown in FIGS. 9 and 10, such a structural design allows the elastic component 6 to be disposed outside of the valve core component 3 within the annular chamber 5. Thus, compared with the thermal expansion valve in the other embodiments of the present application, the axial dimension for assembling the valve core component 3 and the elastic component 6 is reduced, and thus the axial dimension of the thermal expansion valve is reduced, thereby achieving the miniaturization of the thermal expansion valve.

Further, in the above embodiments, the annular chamber 5 further communicates with the balance chamber 14 via the first capillary 41, so that the lower chamber 23 and the balance chamber 14 communicates with each other. The structural design of the connecting hole 151 is omitted in such a structure, thereby simplifying the communicating structure.

Furthermore, as shown in FIGS. 9 and 10, the bottom wall of the annular chamber 5 is provided thereon with a first spring seat 61 for supporting the elastic component 6. Apparently, by assembling the first spring seat 61 with different thicknesses, the elastic force of the elastic component 6 may be regulated, and the degree of superheating of the thermal expansion valve may be thus regulated.

As shown in FIGS. 9 and 10, a guide component 7 is provided outside of the valve core component 3 and is arranged in the inner chamber of the lower end portion of the valve body 1. The balance chamber 14 is sealed to be isolated from the second interface chamber 13 by the guide component 7 and a sealing member 71 arranged on the guide component 7. The opening in the lower portion of the balance chamber 14 is threadingly connected with a valve bonnet 81 configured to support the guide component 7. The guide component 7 is directly supported and positioned by the valve bonnet 81, so that the snap spring 72 for supporting and positioning the guide component 7 may be omitted. Thus, the number of the parts is reduced, and the spending cost and assembling cost are reduced.

Furthermore, as shown in FIGS. 9 and 10, a clamping depression 34 for being clamped by a clamping tool is provided on the external portion of the lower end portion of the valve core component 3 in the balance chamber 14. The clamping depression 34 is flushed with or substantially flushed with the lower pressure-bearing surface of the valve body 1, or higher than the lower pressure-bearing surface of the valve body 1 so as to facilitate the clamping of a clamping tool. After the valve core component 3 is clamped by a clamping tool, the elastic component 6 may be compressed in the valve-opened direction so as to facilitate welding and assembling some assemblies such as the diaphragm 21, the air box cover 25.

Referring to FIGS. 7 and 8, FIG. 7 is a schematic structural view of a thermal expansion valve in a fourth embodiment of the present application; and FIG. 8 is a side view of the thermal expansion valve in FIG. 7.

This embodiment is substantially similar to the technical solutions shown in FIGS. 2 and 3, except that: the elastic component 6 is directly supported by the valve bonnet 81 and is not adjustable. Since the elastic component 6 is not adjustable, the degree of superheating of the thermal expansion valve is not adjustable.

However, in the technical solution shown in FIGS. 2, 4, and 6, the lower end portion of the valve body 1 is assembled with a regulating seat 82 in which a regulating rod 83 is arranged. The upper end portion of the regulating rod 83 is threadingly connected with a second spring seat 62 configured to support the elastic component 6. The upper end of the elastic component 6 further supports the valve core component 3 via the third spring seat 63, and the lower end of the regulating seat 82 is fitted with a valve bonnet 81. By rotating the regulating rod 83 in clockwise or anticlockwise direction, the elastic component 6 may be tightened or loosened, so as to adjust the degree of superheating of the thermal expansion valve.

Referring to FIGS. 13 and 14, FIG. 13 is a schematic structural view of a thermal expansion valve in an eighth embodiment of the present application; and FIG. 14 is a side view of the thermal expansion valve in FIG. 13.

In this embodiment, as shown in FIGS. 13 and 14, the valve core component 3 is of a structure having separated parts, i.e., including an upper segment 36, a middle segment 37 and a lower segment 38. Of course, further, the transmission piece 32 and the upper segment 36 may be of an integral structure, and in this case, the transmission piece 32 can be regarded as a portion of the valve core component 3.

It is to be noted that, in any one of the above embodiments, the upper pressure-bearing surface S5 is a cross section of the valve core component 3 perpendicular to the axis of the valve core component 3 at the position where the sealing member 35 is located, and the lower pressure-bearing surface S6 is a cross section of the valve core component 3 perpendicular to the axis of the valve core component 3 at the position where the sealing member 71 is located. As shown in FIGS. 13 and 14, the upper pressure-bearing surface S5 is a cross section of the upper segment 36 perpendicular to the axis of the upper segment 36 at the position where the sealing member 35 is located, and the lower pressure-bearing surface S6 is a cross section of the lower segment 38 perpendicular to the axis of the lower segment 38 at the position where the sealing member 71 is located.

Furthermore, it is to be noted that, as shown in FIGS. 15-1, 15-2 and 15-3, since the projected area of the upper end surface of the valve core component 3 on the plane perpendicular to the axis of the valve core component 3 is equal to the cross sectional area of the valve core component 3 perpendicular to the axis of the valve core component 3 at the position where the sealing member 35 is located, the upper pressure-bearing surface S5 is also the upper end surface of the valve core component 3. Since the projected area of the lower end surface of the valve core component 3 on the plane perpendicular to the axis of the valve core component 3 is equal to the cross sectional area of the valve core component 3 perpendicular to the axis of the valve core component 3 at the position where the sealing member 71 is located, the lower pressure-bearing surface S6 is also the lower end surface of the valve core component 3.

Furthermore, the present application further provides a refrigerating system, including a compressor, a thermal expansion valve, an evaporator and a condenser. The thermal expansion valve is the one in any of the embodiments described above. An upper chamber 22 is connected to the outlet end of the evaporator via a temperature sensing component, and a lower chamber 23 communicates with the outlet end of the evaporator via a balance tube. Specifically, the refrigerating system may be a thermal pump or an air conditioner. The other portions of the refrigerating system may refer to the prior art, which will not be described herein.

The refrigerating system and the thermal expansion valve thereof according to the present invention are described above in detail. In the description, specific examples are used to illustrate the principle and implementation of the present invention. The description of the embodiments is used only to help better understanding the method and concept of the present invention. It should be noted that, various improvements and modifications can be made to the invention by those skilled in the art without departing from the principle of the present invention, and these improvements and modifications also fall within the scope of protection defined by the claims. 

What is claimed is:
 1. A thermal expansion valve, comprising a valve body, wherein an air box is provided at an upper end of the valve body, an inner chamber of the air box is partitioned into an upper chamber and a lower camber by a diaphragm; a valve core component and a valve port fitted with the valve core component are provided in an inner chamber of the valve body, a lower end portion of the valve body is further provided with a balance chamber configured to balance the valve core component; an upper end portion of the valve core component is arranged in the lower chamber, and a lower end portion of the valve core component is arranged in the balance chamber of the valve body, and wherein the balance chamber communicates with the lower chamber, and is sealed to be isolated from the inner chamber of the valve body.
 2. The thermal expansion valve according to claim 1, wherein a projected area of an upper pressure-bearing surface, subjected to pressure in the lower chamber, of the upper end portion of the valve core component on a plane perpendicular to an axis of the valve core component is substantially equal to a projected area of a lower pressure-bearing surface, subjected to pressure in the balance chamber, of the lower end portion of the valve core component on a plane perpendicular to the axis of the valve core component.
 3. The thermal expansion valve according to claim 1, wherein, when the valve core component and the valve port are closed, a sealing line or a sealing surface between the valve port and the valve core component partitions the inner chamber of the valve body into a first interface chamber and a second interface chamber and wherein a first pressure-bearing surface and a second pressure-bearing surface subjected to opposite forces are provided on a side wall of the valve core component in the first interface chamber.
 4. The thermal expansion valve according to claim 3, wherein a projected area of the first pressure-bearing surface on a plane perpendicular to the axis of the valve core component is substantially equal to a projected area of the second pressure-bearing surface on a plane perpendicular to the axis of the valve core component.
 5. The thermal expansion valve according to claim 3, wherein a third pressure-bearing surface and a fourth pressure-bearing surface subjected to opposite forces are provided on the side wall of the valve core component in the second interface chamber.
 6. The thermal expansion valve according to claim 5, wherein a projected area of the third pressure-bearing surface on a plane perpendicular to the axis of the valve core component is substantially equal to a projected area of the fourth pressure-bearing surface on a plane perpendicular to the axis of the valve core component.
 7. The thermal expansion valve according to claim 5, wherein the valve core component is provided with an inclined sealing surface for sealing the valve port, and wherein when the valve core component and the valve port are closed, the sealing line between the valve core component and the valve port partitions the inclined sealing surface into the second pressure-bearing surface in the first interface chamber and the third pressure-bearing surface in the second interface chamber.
 8. The thermal expansion valve according to claim 1, wherein the balance chamber communicates with an outlet end of an evaporator.
 9. The thermal expansion valve according to claim 8, wherein the valve body is provided therein with a communicating hole communicating with the lower chamber, and the communicating hole communicates with the balance chamber via a first capillary arranged outside the valve body.
 10. The thermal expansion valve according to claim 9, wherein a side wall of the valve body is provided with a first mounting hole communicating with the communicating hole and a second mounting hole communicating with the balance chamber; one end of the first capillary is arranged in the first mounting hole, and the other end of the first capillary is arranged in the second mounting hole.
 11. The thermal expansion valve according to claim 10, wherein the air box comprises an air box base connected to the valve body, and wherein each of the first mounting hole and the second mounting hole is arranged obliquely such as to have a downward inner end and an upward outer end, no matter whether the air box base is positioned upwards or downwards.
 12. The thermal expansion valve according to claim 11, wherein an angle between an axis of the first mounting hole and an axis of the valve body is substantially equal to an angle between an axis of the second mounting hole and the axis of the valve body.
 13. The thermal expansion valve according to claim 10, wherein the air box comprises an air box base connected to the valve body, and wherein no matter whether the air box base is positioned upwards or downwards, the side wall of the valve body is provided thereon with an inclined surface having an inward upper end and an outward lower end, so that the first capillary lies against the inclined surface.
 14. The thermal expansion valve according to claim 9, wherein a capillary groove is provided in the side wall of the valve body, and the first capillary is arranged in the capillary groove.
 15. The thermal expansion valve according to claim 9, wherein a connecting hole is integrally formed and communicates with the communicating hole and is located below the communicating hole, and wherein the connecting hole directly communicates with the balance chamber.
 16. The thermal expansion valve according to claim 1, wherein the upper pressure-bearing surface of the valve core component is connected to a transmission piece with a clearance between the upper pressure-bearing surface and the transmission piece, the valve core component is provided with a valve core component through hole in the axial direction, and the lower chamber communicates with the balance chamber via the valve core component through hole.
 17. The thermal expansion valve according to claim 1, wherein an upper end portion of the valve body is provided with an annular chamber communicating with the lower chamber, and an elastic component is provided in the annular chamber, with a bottom end of the elastic component being supported on a bottom wall of the annular chamber or on a first spring seat, and a top end of the elastic component supporting a transmission piece connected to the valve core component.
 18. The thermal expansion valve according to claim 17, wherein the annular chamber further communicates with the balance chamber via the first capillary.
 19. The thermal expansion valve according to claim 17, wherein a guide component is provided outside of the valve core component and is arranged in the inner chamber of the lower end portion of the valve body, the balance chamber is sealed to be isolated from the second interface chamber by means of the guide component and a sealing member arranged on the guide component, an opening in a lower portion of the balance chamber is threadingly connected with a valve bonnet configured to support the guide component.
 20. The thermal expansion valve according to claim 19, wherein a clamping depression for being clamped by a clamping tool is provided on an external portion of the lower end portion of the valve core component in the balance chamber.
 21. A refrigerating system, comprising a compressor, an evaporator, a condenser, and the thermal expansion valve according to claim 1, wherein the upper chamber is connected to an outlet end of the evaporator via a temperature sensing component, and the lower chamber communicates with the outlet end of the evaporator via a balance tube. 